1. Field of the Invention
This invention relates to aqueous compositions for the protection of paint surfaces. More particularly, it relates to an aqueous composition for the protection of such surfaces which is applied to automobiles, agricultural machinery, construction machinery, and other types of machinery and implements for the purpose of protecting their paint surfaces temporarily.
2. Description of the Prior Art
During the period of time extending from the shipment of commercial products such as automobiles and the like to their delivery to ultimate purchasers, their paint surfaces are often stained by exposure to weather, moisture, sunlight, air, dusts, bird droppings, and atmospheric contaminants such as smoke and the like. This results in an impairment of their commercial value. In recent years, a variety of paint surface protective agents have been developed in order to prevent commercial products from suffering such damage. Among the paint surface protective agents developed for this purpose are, for example, a dispersion of wax in a solvent (as disclosed in Japanese Patent Laid-Open No. 28534/'75), a strippable film-forming composition (as disclosed in Japanese Patent Publication No. 7303/'79) which can be stripped off after use, a dispersion of wax and solid powder in a solvent (as disclosed in Japanese Patent Laid-Open No. 149188/'76 or 62978/'80) which can be wiped off by hand, and an aqueous wax emulsion (as disclosed in Japanese Patent Publication No. 34030/'70).
The paint surface protective agents which are currently in wide use take the form of a dispersion of wax in a solvent or a dispersion of wax and solid powder in a solvent. They form a wax coating by evaporating the greater part of the solvent. The disadvantages of such solvent type compositions have recently been discussed from the viewpoint of environmental protection, resource saving, economy, safety and the like. Moreover, a dispersion of wax in a solvent cannot be removed with steam alone, so that the addition of a small amount of kerosene is required. In order to overcome this disadvantage, there has been proposed a dispersion of wax and solid powder in a solvent wherein the wax and the solid powder are homogeneously mixed to decrease the mechanical strength of the wax coating and thereby facilitate wiping-off of the wax coating. However, the wax coating so formed is defective in protective power. That is, it has the disadvantage of being liable to peel off at a touch and subject to attack by acid rainwater.
On the other hand, an aqueous wax emulsion contains no solvent and, therefore, eliminates the possibilities of environmental pollution and fire hazard. Unlike solvent type compositions, however, this aqueous composition involves a number of additional performance requirements typified by drying properties and dispersibility in water. Moreover, the protective coating formed thereby must be highly resistant to rainwater and moisture and, at the same time, easily removable after use. An aqueous composition which fully satisfies these conflicting performance requirements still remains to be developed.